Ageing and endothelial progenitor cellrelease of proangiogenic cytokines

摘要

SIR—Circulating endothelial progenitor cells (EPCs) arenwidely recognised to contribute to the reparative process ofnResearch lettersn268nDownloaded from ageing.oxfordjournals.org at Institute of Scientific &Technical Info of China on July 21, 2011nthe vascular endothelium and participate in angiogenesis [1].nAlthough declines in the circulating population of EPCs arenassociated with poor cardiovascular disease prognosis and arenpredictive of future adverse cardiovascular events [2], transplantationnof ex vivo expanded EPCs into the coronary arteryncan rescue ischaemic tissue and significantly improve coronarynfunction in patients with myocardial infarction [3]. Thenangiogenic potential of these cells can be explained, in part,nthrough their ability to home to local sites of ischaemia andnvascular damage and secrete potent proangiogenic factors,nsuch as cytokines, chemokines and growth factors, whichnare integral in promoting new blood vessel formation and repair.nFor example, both vascular endothelial growth factorn(VEGF) [4] and granulocyte-colony stimulating factor (GCSF)n[5] stimulate recruitment and migration of EPCs fromnthe bone marrow, inhibit apoptosis and support the angiogenicncapacity of mature endothelial cells [6, 7]. In addition,ninterleukin (IL)-8, a proangiogenic cytokine, has been shownnto attract EPCs to infarcted tissue and enhance the effect ofnG-CSF to mobilise progenitor cells from the bone marrown[8–10]. In older adults, endothelial injury and compromisednEPC-mediated vascular repair are thought to contribute tonatherosclerosis [11]. We have previously reported that EPCncolony-forming capacity, migration and telomere length declinenwith ageing [12, 13]. In the present study, we testednthe hypothesis that the capacity of circulating EPCs to releasenproangiogenic cytokines declines with age in healthy adults.